3-­‐1 Parallel Lines and Transversals When lines do not intersect in the same plane, the lines are parallel ( // ) When lines do not intersect and they are not in the same plane, the lines a skew. A transversal is a line that intersects 2 or more lines Angle Relationships Interior angles Exterior angles int <s ext <s Alternate interior angles Alternate exterior angles alt int alt ext Same side interior angles (consecutive angles) ss int Corresponding angles corresp Same side exterior angles ss ext DIAGRAM 2 1 8 Interior angles int <s Alternate interior angles alt int Same side interior angles (consecutive angles) ss int Corresponding angles corresp l m 6 2 7 3 5 t 4 Exterior angles ext <s Alternate exterior angles alt ext Same side exterior angles ss ext DIAGRAM 3 c 14 1 13
3 Interior angles int <s Alternate interior angles alt int Same side interior angles (consecutive angles) ss int Corresponding angles corresp 6 9 a 2 3 11 16 4 7 d 15 5 8 12 Exterior angles ext <s Alternate exterior angles alt ext Same side exterior angles ss ext 10 b DIAGRAM 4 1 12 a 2 11 4 3 10
00 9 5 6 8 7 c b Interior angles int <s Alternate interior angles alt int Same side interior angles (consecutive angles) ss int Corresponding angles corresp Exterior angles ext <s Alternate exterior angles alt ext Same side exterior angles ss ext t 3.2 Angles and Parallel Lines angles that form a linear pair are supplements Vertical angles are congruent If lines are parallel, corresponding angles are congruent. If lines are parallel, alternate interior angles are congruent. If lines are parallel, alternate exterior angles are congruent. If lines are parallel, same side interior angles a supplements. If lines are parallel, same side exterior angles are supplements t 1 3 line1 4 6 5 7 2 line2 8